Interactive Evolution of Particle Systems for Computer Graphics and Animation

Interactive Evolutionary Computation (IEC) creates the intriguing possibility that a large variety of useful content can be produced quickly and easily for practical computer graphics and gaming applications. To show that IEC can produce such content, this paper applies IEC to particle system effects, which are the de facto method in computer graphics for generating fire, smoke, explosions, electricity, water, and many other special effects. While particle systems are capable of producing a broad array of effects, they require substantial mathematical and programming knowledge to produce. Therefore, efficient particle system generation tools are required for content developers to produce special effects in a timely manner. This paper details the design, representation, and animation of particle systems via two IEC tools called NEAT Particles and NEAT Projectiles. Both tools evolve artificial neural networks (ANN) with the NeuroEvolution of Augmenting Topologies (NEAT) method to control the behavior of particles. NEAT Particles evolves general-purpose particle effects, whereas NEAT Projectiles specializes in evolving particle weapon effects for video games. The primary advantage of this NEAT-based IEC approach is to decouple the creation of new effects from mathematics and programming, enabling content developers without programming knowledge to produce complex effects. Furthermore, it allows content designers to produce a broader range of effects than typical development tools. Finally, it acts as a concept generator, allowing content creators to interactively and efficiently explore the space of possible effects. Both NEAT Particles and NEAT Projectiles demonstrate how IEC can evolve useful content for graphical media and games, and are together a step toward the larger goal of automated content generation.     

Qualitatively faithful quantitative prediction

We describe an approach to machine learning from numerical data that combines both qualitative and numerical learning. This approach is carried out in two stages: (1) induction of a qualitative model from numerical examples of the behaviour of a physical system, and (2) induction of a numerical regression function that both respects the qualitative constraints and fits the training data numerically. We call this approach Q² learning, which stands for Qualitatively faithful Quantitative learning. Induced numerical models are “qualitatively faithful” in the sense that they respect qualitative trends in the learning data. Advantages of Q² learning are that the induced qualitative model enables a (possibly causal) explanation of relations among the variables in the modelled system, and that numerical predictions are guaranteed to be qualitatively consistent with the qualitative model which alleviates the interpretation of the predictions. Moreover, as we show experimentally the qualitative model's guidance of the quantitative modelling process leads to predictions that may be considerably more accurate than those obtained by state-of-the-art numerical learning methods. The experiments include an application of Q² learning to the identification of a car wheel suspension system—a complex, industrially relevant mechanical system.     

Viscosity Measurements of Potato Starch Paste with the Rapid Visco Analyzer

Viscosity behaviour of potato starch paste was measured with the Rapid Visco Analyzer (RVA, Newport Scientific, Warriewood, Australia). By reason of high viscosity properties of potato starch suspensions, starch concentration was reduced from 3.0 to 2.0 g starch weight (14% moisture) in 25 ml distilled water. In view of Brabender viscograms a short temperature profile (13 min including heating, stable hot phase, and cooling) achieved the best results. Reproducibility of RVA-measurements was high as well with new canisters as with re-used ones. Coefficient of variation (s%) was below 2%. A comparison of RVA and Brabender viscograms pointed out a close correlation of r=0.94 for both, the peak viscosity and the viscosity difference between peak and trough.     

The relationship between some chemical parameters and sensory evaluations for plain black tea (Camellia sinensis) produced in Kenya and comparison with similar teas from Malawi and South Africa

Reliable and accurately measurable chemical parameters that can be used to estimate black tea quality are desirable in trade, research and breeding programmes. Using plain Kenyan black tea from 11 cultivars, which gave some significant differences in their plain black tea quality parameters, the individual theaflavins composition, total theaflavins, thearubigins, theaflavin digallate equivalent, total colour and brightness were determined. The parameters were regressed against sensory evaluation scores of two tasters A and B. The theaflavin digallate equivalent (TDE) showed the strongest relationship (r = 0.71 (P ? 0.01) and r = 0.80 (P ? 0.001)) for A and B′, respectively. The simple (non gallated) theaflavin and thearubigins did not show significant relationships with sensory evaluation. Of the liquor characteristics, there were significant relationships between liquor brightness and sensory evaluation by A and B (r = 0.58 (P ? 0.06) and r = 0.59 (P ? 0.05)), respectively. In consequence, TDE and brightness can be used in tea breeding programmes as quality indicators or to estimate plain black tea quality potential in the tea trade. Optimising their levels can also help to produce good quality Kenyan black teas during processing. Comparison of these results with work published earlier indicates that, of the individual theaflavins, theaflavin-3,3′-digallate correlates best with tea taster scores for the 11 Kenyan cultivars, whereas the simple theaflavin correlates best with tea tasters’ scores for 40 Malawian cultivars. However, the derived parameter, TDE correlates very well with tea tasters’ scores for all of the above cultivars.     

Inhibition of tumor necrosis factor alpha alters resistance to Mycobacterium avium complex infection in mice

Increased production of tumor necrosis factor alpha (TNF-alpha) appears to play an important role in the progression of human immunodeficiency virus disease. One treatment strategy being explored is the use of TNF-alpha inhibitors. TNF-alpha also appears to be important in conferring resistance to infections, and the inhibition of this cytokine may exacerbate the emergence of opportunistic pathogens, such as Mycobacterium avium complex (MAC). The present study examines the possibility that inhibition of TNF-alpha will increase the progression of disease in mice infected with MAC. C57BL/6 beige (bg/bg) mice have been shown to be highly susceptible to infection with MAC and are routinely used for testing of antimycobacterial drugs. However, bg/bg mice are known to exhibit impaired phagocyte and natural killer cell function. Since these cell types are important sources of TNF-alpha, the susceptibility of the bg/bg strain to infection with MAC was compared with those of the heterozygous (bg/+) and wild-type (+/+) strains of C57BL/6 mice. The susceptibilities of the bg/bg and bg/+ strains of mice infected with MAC were found to be comparable. The +/+ strain was the least susceptible. Mycobacterial burden and serum TNF-alpha levels increased over time in all the strains of mice tested. The bg/+ strain of C57BL/6 mice was then chosen to measure the activity of TNF-alpha antagonists. Treatment with dexamethasone decreased serum TNF-alpha levels and increased mycobacterial burden. Treatment with anti-TNF-alpha antibody or pentoxifylline did not significantly alter serum TNF-alpha levels but increased mycobacterial burden. Treatment with thalidomide neither consistently altered mycobacterial burden in the spleens or livers of infected mice nor affected serum TNF-alpha levels.     

Efficient integration of a realistic two-dimensional cardiac tissue model by domain decomposition

The size of realistic cardiac tissue models has been limited by their high computational demands. In particular, the Luo-Rudy phase II membrane model, used to simulate a thin sheet of ventricular tissue with arrays of coupled ventricular myocytes, is usually limited to 100 x 100 arrays. We introduce a new numerical method based on domain decomposition and a priority queue integration scheme which reduces the computational cost by a factor of 3-17. In the standard algorithm all the nodes advance with the same time step delta t, whose size is limited by the time scale of activation. However, at any given time, many regions may be inactive and do not require the same small delta t and consequent extensive computations. Hence, adjusting delta t locally is a key factor in improving computational efficiency, since most of the computing time is spent calculating ionic currents. This paper proposes an efficient adaptive numerical scheme for integrating a two-dimensional (2-D) propagation model, by incorporating local adjustments of delta t. In this method, alternating direction Cooley-Dodge and Rush-Larsen methods were used for numerical integration. Between consecutive integrations over the whole domain using an implicit method, the model was spatially decomposed into many subdomains, and delta t adjusted locally. The Euler method was used for numerical integration in the subdomains. Local boundary values were determined from the boundary mesh elements of the neighboring subdomains using linear interpolation. Because delta t was defined locally, a priority queue was used to store and order next update times for each subdomain. The subdomain with the earliest update time was given the highest priority and advanced first. This new method yielded stable solutions with relative errors less than 1% and reduced computation time by a factor of 3-17 and will allow much larger (e.g., 500 x 500) models based on realistic membrane kinetics and realistic dimensions to simulate reentry, triggered activity, and their interactions.     

High burnup performance of annular UO2 fuel with inter-pellet graphite discs

We have irradiated annular UO₂ fuel with inter-pellet graphite discs at linear powers of 62 and 44 kW/m to a maximum burnup of 775 MWh/kgU (32000 MWd/TeU). The combination reduced fission gas release by up to a factor of four compared with that for annular fuel alone, for absolute releases up to 45%. Disc compatibility with other fuel components was acceptable.     

Entrainment of the circadian system of mammals by nonphotic cues

Although light is the principal zeitgeber to the mammalian circadian system, other cues can be shown to have a potent resetting effect on the clock of both adult and perinatal mammals. Nonphotic entrainment may have both biological and therapeutic significance. This review focuses on the effect of behavioral arousal as a nonphotic cue and the neurochemical circuitry that mediates arousal-induced entrainment in the adult rodent. In addition, it considers the role of nonphotic entrainment of the developing circadian system in perinatal life prior to the establishment of retinal input to the clock.     

Metacarpal and phalangeal fractures in athletes

The high demands placed on the upper extremity in sporting activities subject the competitive athlete to common injuries of the hand. Treatment options are based on the fracture configuration, associated extremity injuries, and status of the surrounding soft tissue. Metacarpal and phalangeal fractures may usually be treated by closed, nonoperative methods, and most athletes may quickly return to play with a protective orthosis. Supplemental methods of fixation, such as percutaneous pins and tension-band wires, may be used for unstable fractures. When required, open reduction and internal fixation can provide optimum stability to the fracture, which allows immediate range-of-motion and early return to play.